Magnetron device



2 Sheets-Sheet 1 INVENTOR.

MAGNETRON DEVICE July 12, 1960 R. M. scANzANl Filed March 25, 1957ROBERT M. SCANZ AN July 12, 1960 R. M. scANzANl MAGNETRON DEVICE 2Shee'ts-'Sheeifl 2 Filed March 25, 1957 INVENToR.

IZOBEIZT M. SCANZAN\ AT1-02N EY MAGNETRON DEVICE Robert M. Scanzani,Beverly, Mass., assgnor to Bomac Laboratories Inc., Beverly, Mass., acorporation of Massachusetts Filed Mar. 25, .1957, Ser. No. 648,240

2 Claims. (Cl. SI5-B951) The present invention relates generally toelectron discharge `devices of the magnetron type and Aspecically, tonovel structure for positioning and adjusting the cathode electrode.

Magnetrons primarily comprise'a multicavity anode electrode with acathode electrode concentrically disposed therein. In the manufacture ofsuch devices the positioning of the cathode is extremely critical andthe tolerances allowed are very small. Packaged magnetrons provide acathode structure which extends axially through a component of themagnetic circuit forming a part of the envelope and is supported at adistance from the anode-cathode interaction space. (Following assemblyof the cathode component to the tube envelope, further adjustment isimpossible. Hence careful control with appropriate jigging is necessaryto assure accurate alignment.

The present invention, therefore, has for its principal object theprovision of a novel cathode positioning and adjusting mechanism Iformagnetrons to facilitate alteration of anode-cathode spacings in afinished tube.

Another object is to provide a novel electrode positioning and adjustingmechanism for magnetrons which permits both lateral and axialdisplacement of the cathode in a finished tube.

'I'he objects enumerated are attained vby means of a housing membersurrounding the cathode assembly supporting structure. A bearing racemember is positioned within the housing yand threadably engages thecathode electrode tubular extension. A plurality of hall bearings arespaced within the housing member and engage the bearing race member.Threaded studs having a tapered center portion are positioned Withinhubs circumferentially `disposed around the housing member with thetapered portion engaging the ball bearings. Ax-ial movement of the studswill result in lateral displacement of the cathode electrode. Further,rotation of the bearing race member will result in axial displacement ofthe electrode. A diaphragm member cooperates with the cathode supportstructure to permit axial movement without loss of the vacuum conditionof the tube.

Other objects, features land advantages will ibecome apparent afterconsideration of the following detailed specification and the appendeddrawings, in which:

Fig. 1 is a perspective view partly in section of the ernbodiment;

Fig. 2 is a view-taken along the line 2-2 in IFig. 1;l

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l2,945,159 latented July 12, 1960 ice rial form with a body member 3 theenvelope of the embodiment. Tubular member 4 secured to pole piece 1provides means for evacuation of the envelope and a dielectric tip-olfseal 5 encloses the end thereof to preserve the vacuum condition. Iln atunable magnetron member 4 would be utilized to position the tuningmechanism and a separate tubulation could be provided for evacuation.Multicavity anode 6 having a central opening therethrough is positionedwithin cylinder 3, as shown. The output coupling means 7 may be securedto the outer surface of cylinder 3 and communicates with a slot 35 inthe multicavity anode 6.

A support cylinder 8 is sealed to the wall of recess 9 in the outer faceof pole piece 2. In the method of assembling the embodiment the envelopecomprising pole pieces 1 and 2 and cylinder 3 together with member 4 andcylinder 8 may be fabricated as a separate sub-assembly. This preventscontamination of the electrodes during the metal brazing or weldingprocess. The overall cathode structure together with the positioning andadjusting mechanism of the invention may be completely subassembled andthen joined to the cylinder 8 by means of a glass seal 10 to completethe tube prior to exhaustt Cathode electrode 1-1 concentricallypositioned within the central opening in anode 6 is mounted upon anelongated hollow tubular extension 12 which extends axially through thepassageway defined in pole piece 2. A heat radiator 13 may be providedadjacent to the cathode and this component extends partly into polepiece `r1. VThe cathode 11 may be of the indirectly heated type with theheater concentrically disposed within the cathode and a conductor `14axially ldisposed within extension 12. Conductor 14 is supported by adielectric insulator 15 and the outer end 16 is connected to the heatersupply. The adjusting mechanism is shown generally at 17 and is securedto sleeve 18 which is in turn joined by glass seal 10 to cylinder V8. Yc

Referring now to lFigs. 2, 3 and 4 the teachings ofthe presentVinvention will be described. Cylindrical housing member 19 having acentral opening is provided with a shoulder 20 to which sleeve 18 issecured. Aplurality of hub. portions '21 are spaced around the outersurface thereof with each hub havin-g a passageway V22 extendingparallel to the axis of the tubular extension 12. Another passageway 23perpendicular to the tube axis is also provided. Passageway -22 isthreaded as at 24 at one end to receive the threaded portion 25 ofadjusting stud 26. The center portion 27 of stud 26 is tapered as shownand bears against ball bearing 28 which is inserted through passageway23 prior to the introduction of the stud in the hub passageway 22.

`Coaxially disposed within housing member 19 and secured to cathodetubular extension 12 as shown is a sleeve 29 having a threaded outersurface 30. Bearing race member 31 is threaded on sleeve 29 and isprovided with slots 32 to receive a tool for rotation of member 31. Agroove 33 provides means for engaging the =ball bearings 28.

Diaphragm 34 of a metal such as Monel is secured between the inner endof member '19 and tubular extension 12 to retain the vacuum condition ofthe tube as the cathode is positioned or adjusted in the manner now tobe described.

After assembly of the magnetron device including mounting of the cathodesub-assembly and completion of seal 10, the exhausting and tip-ottprocess steps are periformed. The device is then electrically tested andthe cathode may be adjusted for maximum eiciency. The lateral adjustmentyis provided by means of axial movement of studs 26 Within hubs 21. 'Ihemovement of tapered portion 27 results in displacement of bearings 28 tothereby adjust the cathode laterally. Another precision adjustment isprovided -by the invention in-thatmember-lnllmayV be rotated byinsertion of asu-itable tool such as a-spanner wrench inholes V32,.Since bearings-@Safe positionedY within- `groove 33 and are' lockedWithin^ passagevvay 23 movement of member 31 results in axial:displacement of the'cathode. Y

j There is; thus disclosed at simple and -eicient vpositioning andadjusting mechanism whichpermits very precise adjustmentof anode-cathodespacings inmagnetron devicesafter assembly at the production-tacilitytFurther, after operation when changes in performance may occur it ispossible, by adjustment-of thecathode, to bring many of these deviceswithin the-realmo-f operativev tubes when prior art tubes would normallybe replaced.l Neither of these advantages may be found in existingmagnetron devises.

What is' claimed is :g

l. A magnetron tube comprising aV mult-icavity anode member having acentral opening, magnetic pole pieces positioned at opposite ends ofsaid anode member, cathode supporting meanssecured to one of said polepieces, acathode electrode extending axially through said pole piece andsupporting means With its inner end concentrically positioned withinsaid central opening, means forl positioningl and adjusting said cathodeYelectrode vmounted on Ysaid supporting means, said `adjustingmeanscompris'- ing--a cylindrical housing member having aY plurality ofradial hubs circumferentially disposed thereon, `each hub having anaxially movable threaded stud having a tapered intermediate portion, arotatable member threada-bly secured to said cathode electrode in theregionl adjacent to said cylindrical housing member, `a plurality ofball bearing members positioned within said cylindrical housingincontact with said rotatable member and the tapered portion of each ofsaid threaded studs, said cathode electrode being displaced axially byrotation of said rotatable member and laterally by axial movement ofsaid threaded studs.

2. A- magnetronk tube comprising a multicavity anode member having acentral opening, magnetic pole pieces positioned -at opposite ends ofsaid anode member, at least one of said pole pieces having an axialpassageway, a support cylinder secured to the outer face of said polepiece, a cathode electrode having a tubular extension extending throughsaid axial passageway with its inner end concentrically disposed withinsaid anode central opening, cathode supporting structure insulatinglysealed to said support cylinder, means for 'adjusting'and positioningsaid cathode electrode mounted on said cathode supporting structure,said means comprising a cylindrical housing member having a plurality'of hub portions along the outer peripheral Wall, each hub portionhousing a threaded stud positioned to move parallelto the tube axis,said threaded studs having a tapered non-threaded intermediate portion,a sleeve secured" to said cathode electrode tubular extension in theregion adjacent to said housing member, a bearing race member threadablysecured to said sleeve, `an annularV groove'. defined along the outerperipheral'wall of'saidbearing race member, a'ball'bearingmemberpositionedwithin*eachhub portion in contact withy said tapered portionof said studs and said bearing member groove, said cathode electrodebeing displaced axially fby rotationV 'of said bearing race member andlaterally by axialmovement of said threaded studs;

References cited in the fue ofth'is patent UNITED 'STATES P'rfinrrrsV

